Control of a soft robotic link using a fractional-order controller

The purpose of this work is to present a novel control approach for a tendondriven elastic continuum mechanism using a Fractional-Order (FO) controller. The mechanism is composed of a silicon continuum, tendons and antagonistic actuation which yields a highly complex mechanical model. This model is heavily simplified to that of a linear time invariant second-order system and a robust control approach is applied to cope with the neglected dynamic effects. Apart from the specifications for the speed and the overshoot of the system response, the controller must be extensively robust to model parameter mismatches and uncertainties. The FO controller is used to meet the control specifications, taking advantage of the introduction of its fractional order α. Simulation and experimental data are presented to validate the approach in comparison to results from two standard integer-order controllers that are designed using the same specifications.